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Determination of Moisture (Drying method (Infrared drying methods - Rapid,…
Determination of Moisture
Chemical methods
Karl Fischer Titration
Advantages
Good for high fat foods
Good for low and intermediate moisture food
Disadvantages
Toxic chemicals
Not good for high fibrous foods
Electrical method
Advantages
•Very fast, < 1 min/sample
•Very portable
•Inexpensive, ~$300
•Work with whole grain directly
Disadvantages
Accuracy is not as good as other methods
Not good for samples with high moisture content (>20%)
Drying method
Infrared drying methods - Rapid
Pros: 10 - 15 min drying time; portable
Cons: Not as accurate as the air oven drying methods
Microwave drying methods - Rapid
Pros: fast
Vacuum oven methods
Freeze-drying methods (or Lyophilization)
Pros: A very gentle technique, will not decompose sample
Cons: A very slow technique, 18-72 hours
Air oven methods
Limitations
Samples contain a lot of volatile compounds
Samples contain high sugar contents
Some samples can not be heated to 130 °C
Distillation method
Advantages
Good for hygroscopic samples, e.g., milk powders
Good for samples contain volatile compounds other than water
Disadvantages
•Hard to get clear separation between the water and toluene layer in the collection tube (get emulsion)
•Can only do one sample at a time
•Not good choice for high fat foods, e.g., chocolate, butter
Near Infrared (NIR) Spectroscopy Method